Parallel robots

Abstract

This invention provides a parallel robot, comprising: a base, a movable component, and a plurality of robotic arms connecting the base and the movable component in parallel; each robotic arm includes: a drive link driven to rotate by a motor disposed on the base; two parallel passive links connecting the drive link to the movable component; a ball joint disposed between each passive link and the drive link and between each passive link and the movable component; and a mounting mechanism for detachably mounting each ball joint to the drive link or the movable component; each ball joint includes: a ball head and a fixing portion integrally formed on the ball head; wherein at least one mounting mechanism includes: a first threaded hole disposed on the fixing portion; a second through hole disposed on the drive link or the movable component; and a screw component passing through the second through hole and fastened to the first threaded hole.

Description

[Technical Field]

[0001] This invention relates to a parallel robot. [Previous Technology]

[0002] A parallel robot is currently known, which includes three robotic arms that connect a base and a movable part in parallel; and each robotic arm includes: a drive link driven by a motor; and two parallel passive links connected to the drive link and the movable part (for example, see Patent Document 1). The drive link and the two passive links, and the two passive links and the movable part are respectively connected by ball joints in a rotatable manner.

[0003] The two passive linkages of each robotic arm are positioned to clamp the drive linkage and movable part from both sides along an axial direction parallel to the rotation axis of the drive linkage. Threaded holes are provided on both sides of the drive linkage and movable part along this axial direction. The ball joint is secured by the external thread of the ball head, which is fixed to the threaded hole. [Prior Art Documents] [Patent Documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 2019-119017 [Summary of the Invention]

[0005] To exchange the ball joint, the screw must be rotated to loosen its fastening to the threaded hole, and the ball joint must be moved along an axis parallel to the rotation axis of the drive link. Therefore, to remove the ball joint from the drive link or movable part, it must be moved in a direction that widens the gap between the two driven links.

[0006] To ensure that the two passive links of each robotic arm remain parallel even during high-speed operation, a support link is sometimes installed. This support link spans the two passive links and is configured to rotate about an axis orthogonal to the major axis of the passive links. In this case, when exchanging ball joints, it is necessary to expend considerable effort to separate the support link from the passive links. Therefore, it is desirable to be able to exchange ball joints without moving them in a direction that widens the gap between the two passive links.

[0007] One embodiment of the present invention is a parallel robot, comprising: a base portion; a movable component disposed relative to the base portion with a gap; and a plurality of robotic arms connecting the base portion and the movable component in parallel; and each robotic arm comprising: a drive link driven to rotate by a motor disposed on the base portion; two parallel passive links connecting the drive link to the movable component; ball joints disposed between each passive link and the drive link and between each passive link and the movable component; and a mounting mechanism for detachably mounting each ball joint to the base portion. The drive link or the movable component; and each of the aforementioned ball joints includes: a ball head and a fixing portion integrally formed on the ball head; and at least one of the aforementioned mounting mechanisms between the aforementioned passive link and the aforementioned drive link of each of the aforementioned robotic arms and between the aforementioned passive link and the aforementioned movable component includes: a first threaded hole or a first through hole disposed on the aforementioned fixing portion; a second through hole or a second threaded hole disposed on the aforementioned drive link or the aforementioned movable component; and a screw component that passes through the aforementioned first through hole and is fastened to the aforementioned second threaded hole, or passes through the aforementioned second through hole and is fastened to the aforementioned first threaded hole.

Implementation Method

[0009] The parallel robot 1 of the first embodiment of the present invention will be described below with reference to the drawings. As shown in FIG1, the parallel robot 1 of this embodiment includes: a base 2 fixed to a ceiling or a platform; movable parts 3 arranged at intervals below the base 2; and three robotic arms 4, 5, and 6 connected in parallel with the base 2 and the movable parts 3.

[0010] The base 2 is equipped with three servo motors (motors) 7, 8, and 9, which are used to drive the three robotic arms 4, 5, and 6 respectively. Each robotic arm 4, 5, and 6 includes: drive links 10, 11, and 12, which are driven to rotate about a horizontal axis of rotation A by the respective servo motors 7, 8, and 9; and two parallel rod-shaped passive links 13, 14, and 15, which connect the drive links 10, 11, and 12 to the movable part 3. The three drive links 10, 11, and 12 are arranged at equal intervals around a central axis B, which extends vertically with the center of the base 2 as the center.

[0011] As shown in FIG. 2, each of the passive links 13, 14, and 15 is equipped with a ball joint 16 at both ends. The ball joint 16 connects the passive links 13, 14, and 15 relative to the drive links 10, 11, and 12 and the movable part 3 in a manner that allows rotation. The ball joint 16 has a ball head bolt 19 and a socket 20. The ball head bolt 19 has a ball head 17 and a cylindrical bolt (fixing part) 18 extending radially outward from the outer surface of the ball head 17. The socket 20 has an inner spherical surface 16a, which partially covers the outer peripheral surface of the ball head 17 and supports the ball head 17 in a manner that allows it to move around a center point. By rotating the ball head 17 around the center point within the socket 20, the bolt 18 can be tilted in any tilting direction.

[0012] In the example shown in Figure 2, sockets 20 are fixed at both ends of the passive connecting rods 13, 14, and 15. The ball head bolts 19 are supported in a direction orthogonal to the major axis of the passive connecting rods 13, 14, and 15, so that they can rotate relative to the passive connecting rods 13, 14, and 15 within a predetermined angle range. The end face of the bolt 18 is provided with a threaded hole (first threaded hole) 21 along the axial direction of the bolt 18.

[0013] As shown in Figures 2 and 3, a support link 22 spans between the two passive links 13, 14, and 15 of each robotic arm 4, 5, and 6. The support link 22 comprises: two support plates 23 positioned on both sides that radially enclose the two passive links 13, 14, and 15; a shaft 24 fixed to the passive links 13, 14, and 15; and bearings 25 installed to allow each support plate 23 to rotate about an axis C orthogonal to the major axis of the passive links 13, 14, and 15. In the figures, symbol 26 represents a washer used to preload and adjust the bearing 25 to an appropriate length, and symbol 27 represents a bolt that mounts the washer 26 between the two support plates 23.

[0014] In response to the rotation of the two passive links 13, 14, and 15 relative to the drive links 10, 11, and 12, the support link 22 will rotate relative to the passive links 13, 14, and 15. Therefore, even if the passive links 13, 14, and 15 rotate relative to the drive links 10, 11, and 12 with drastic acceleration and deceleration, the two passive links 13, 14, and 15 of each robotic arm 4, 5, and 6 can still maintain parallelism.

[0015] As shown in Figures 1 and 2, each drive link 10, 11, and 12 has two plate-shaped mounting portions 28 at the positions where the driven links 13, 14, and 15 are mounted. These two plate-shaped mounting portions 28 extend along a plane orthogonal to the rotation axis A and are spaced apart in the direction of the rotation axis A. As shown in Figure 2, each mounting portion 28 has a through hole (second through hole) 29, which is parallel to the rotation axis A and extends coaxially. The spacing between the outer surfaces of the two mounting portions 28 is set to be equal to the spacing between the end faces of the ball head bolts 19 when their long axes are aligned with the same straight line as the ball head bolts 19 mounted on the two driven links 13, 14, and 15.

[0016] The drive links 10, 11, and 12 are fixed to the ball head bolts 19 mounted on the driven links 13, 14, and 15 by means of bolt components (screw components) 30 that pass through the through holes 29 of the mounting portions 28 of the drive links 10, 11, and 12 from the inside side. The bolt components (screw components) 30 are fastened to the threaded holes 21 of the ball head bolts 19. The bolt component 30 has a fitting portion 30c between its external thread 30a at one end and its head 30b at the other end, which engages with the through holes 29 of the mounting portions 28. This allows the ball head bolts 19 to be fixed in a position positioned within the mounting portions 28 of the drive links 10, 11, and 12.

[0017] The movable part 3, as shown in FIG2, has a plate-shaped mounting portion 31 at the position where 3 sets of 6 passive connecting rods 13, 14, and 15 are installed (2 of which are shown in FIG2). The plate extends from the outer peripheral surface to the outer side of the radial direction along a plane parallel to the central axis D. Each of the 2 mounting portions 31 in each set has a through hole (second through hole) 32, and the through hole (second through hole) 32 is arranged parallel to each other at intervals in the tangential direction around the central axis D and extends coaxially in the tangential direction.

[0018] Furthermore, the spacing between the outer surfaces of the two mounting portions 31 is set to be equal to the spacing between the end faces of the ball head bolts 19 when the long axes of the ball head bolts 19 mounted on the two passive connecting rods 13, 14, and 15 are aligned on the same straight line. In this embodiment, the mounting mechanism consists of the following: a first threaded hole 21 provided in the bolt 18; second through holes 29 and 32 provided in the mounting portions 28 and 31 of the drive connecting rods 10, 11, 12, or movable parts 3; and a bolt member 30 passing through the second through holes 29 and 32 and fastened to the first threaded hole 21.

[0019] The movable part 3 and the ball head bolt 19 mounted on the passive connecting rods 13, 14, and 15 are fixed by a bolt member 30 passing through the through hole 32 of the mounting portion 31 of the movable part 3 and fastened to the threaded hole 21 of the ball head bolt 19. The bolt member 30 has a fitting portion 30c between its external thread 30a at one end and its head 30b at the other end, which engages with the through hole 32 of the mounting portion 31. In this way, the ball head bolt 19 can be fixed in a state where it is positioned in the mounting portion 31 of the movable part 3.

[0020] The following explains the function of the parallel robot 1 configured as described in this embodiment. According to the parallel robot 1 of this embodiment, by synchronously driving three servo motors 7, 8, and 9, the movable part 3 can be kept in a horizontal posture and moved parallel to the desired 3D position.

[0021] Because the parallel robot 1 causes the movable part 3 to move at high speed, the ball joint 16, which connects the drive links 10, 11, 12 to the passive links 13, 14, 15 and the passive links 13, 14, 15 to the movable part 3, will rotate frequently and repeatedly. Therefore, the condition of the ball joint 16 must be checked regularly, and maintenance work such as replacement must be performed when there is wear and tear.

[0022] According to this embodiment, to exchange the ball joints 16 connecting the passive links 13, 14, 15 and the drive links 10, 11, 12, firstly, as shown in FIG4, the bolt components 30 fastened to the threaded holes 21 of the ball head bolts 19 of the ball joints 16 of the two passive links 13, 14, 15 must be loosened, that is, the bolt components 30 fastened to the threaded holes 21 must be loosened and removed. When removing the bolt components 30, the bolt components 30 are moved to the direction of being pulled out from the inner side of the mounting portion 28 of the drive links 10, 11, 12, and then removed. Therefore, the bolt components 30 can be removed without changing the spacing of the ball heads 17 of the two ball head bolts 19.

[0023] After the bolt component 30 is pulled out from the through hole 29, as shown in FIG5, the drive links 10, 11, 12 and the driven links 13, 14, 15 can be separated by moving the drive links 10, 11, 12 and the driven links 13, 14, 15 relative to each other along the outer side of the mounting portion 28 in the direction of arrow A. Furthermore, in the state of being separated from the drive links 10, 11, 12, the ball joint 16 can be easily removed from the ends of the driven links 13, 14, 15, thereby allowing for the replacement of a new ball joint 16.

[0024] Next, following the reverse procedure described above, the ball head bolts 19 are positioned so that their long axes are aligned with the bolts 18 of the new ball joints 16 installed on the two driven connecting rods 13, 14, and 15. In this state, the mounting portions 28 of the drive connecting rods 10, 11, and 12 are inserted between the end faces of the ball head bolts 19 in the direction of arrow B. Furthermore, the external threads 30a of the bolt components 30 passing through the through holes 29 of the two mounting portions 28 are tightened into the threaded holes 21 of the two ball head bolts 19. This completes the replacement of the ball head bolts 19.

[0025] Thus, according to the parallel robot 1 of this embodiment, when exchanging the ball joints 16 used to connect the drive links 10, 11, 12 and the two passive links 13, 14, 15, it is not necessary to change the spacing of the ball heads 17 of the two ball joints 16 to be exchanged. The spacing of the ball heads 17 of the two ball joints 16 connecting the drive links 10, 11, 12 and the two passive links 13, 14, 15 is fixed by the support link 22 and the two ball joints 16 connecting the movable part 3 and the two passive links 13, 14, 15. Since the spacing of the ball heads 17 does not change during the exchange, the ball joints 16 can be exchanged without the large-scale work of disassembling the support link 22 or removing the connection between the movable part 3 and the passive links 13, 14, 15.

[0026] In particular, when the two support plates 23 constituting the support link 22 are firmly fixed by adhesive, the adhesive must be peeled off in order to disassemble the support link 22, making the disassembly operation of the support link 22 more difficult. According to this embodiment, the ball joint 16 can be replaced without disassembling the support link 22, which has the advantage of significantly reducing the time required for the operation.

[0027] Furthermore, the ball joints 17 of the ball joints 16 connecting the movable part 3 and the passive links 13, 14, 15 are spaced apart by the support link 22 and the two ball joints 16 that connect the drive links 10, 11, 12 and the two passive links 13, 14, 15. Therefore, when performing operations such as replacing the ball joints 16 between the movable part 3 and the passive links 13, 14, 15, the steps are the same as those for the ball joints 16 between the drive links 10, 11, 12 and the passive links 13, 14, 15, and the replacement can be easily performed without a large-scale project.

[0028] Furthermore, according to the parallel robot 1 of this embodiment, a pair of passive links 13, 14, 15, ball joints 16 installed at both ends of the passive links 13, 14, 15, and support links 22 installed on the passive links 13, 14, 15 can be operated as passive link units (units). That is, they can be manufactured and managed as passive link units, which not only facilitates maintenance operations but also has the advantage of being easy to assemble.

[0029] Furthermore, in this embodiment, the ball head bolt 19 is fixed in a state where it is positioned on the drive linkage 10, 11, 12 or the movable part 3, and the through holes 29, 32 provided in the mounting portions 28, 31 of the drive linkage 10, 11, 12 or the movable part 3 engage with the fitting portion 30c of the bolt member 30 that is fastened to the threaded hole 21 of the ball head bolt 19. Alternatively, as shown in FIG6, a pin hole 33 parallel to the threaded hole 21 may be provided in the bolt 18 of the ball head bolt 19, and a pin hole 34 parallel to the through holes 29, 32 may be provided in the mounting portions 28, 31. In this way, when the pin 35 is positioned by engaging with the pin hole 33 of the bolt 18 and the pin hole 34 of the mounting parts 28 and 31, the bolt 30, which has through holes 29 and 32 but does not have an engaging part 30c, will be tightened into the threaded hole 21 of the bolt 18, thereby fixing the ball head bolt 19 to the drive linkage 10, 11, 12 or the movable part 3.

[0030] Furthermore, instead of inserting the drive linkage 10, 11, 12 or the movable part 3 between the end faces of the bolt 18 into the mounting portion 31, as shown in FIG7, the bolt 18 can also be formed in a flat plate shape, and the drive linkage 10, 11, 12 or the movable part 3 can overlap in the thickness direction of the bolt 18 and be fixed in this state. In the example shown in the figure, the bolt 18 is provided with a through hole (first through hole) 36 and a pin hole 37 that are through in the thickness direction of the plate. The pin hole 37 is parallel to the through hole 36. The drive linkage 10, 11, 12 is provided with a threaded hole (second threaded hole) 38 and a pin hole 39 extending in the thickness direction on the flat mounting portion 28 that is parallel to the rotation axis A.

[0031] Furthermore, when positioned by the pin 40 that engages with the pin hole 37 of the bolt 18 and the pin hole 39 of the mounting part 28, the bolt 30 that passes through the through hole 36 is fastened to the threaded hole 38 of the mounting part 28, thereby fixing the ball head bolt 19 to the drive linkage 10, 11, 12 or the movable part 3. At this time, the first through hole 36 provided in the fixed part, i.e., the bolt 18, the second threaded hole 38 provided in the mounting parts 28, 31 of the drive linkage 10, 11, 12 or the movable part 3, and the bolt member 30 that passes through the first through hole 36 and is fastened to the second threaded hole 38 can constitute a mounting mechanism.

[0032] Furthermore, the parallel robot 1 has three robotic arms 4, 5, and 6, but it can also have any number of robotic arms, more than two. In addition, the above description is based on the case where the ball joint 16 connecting the drive links 10, 11, 12 and the passive links 13, 14, 15 and the ball joint 16 connecting the movable part 3 and the passive links 13, 14, 15 have the same structure, but it is not limited to this and only one of the cases may be used.

[0033] Furthermore, in the above embodiments, the bolt 18 is shown to have a threaded hole 21 or a through hole 36. However, as shown in FIG8, a structure can also be adopted, including: a bolt 18 with external threads 41, and a connector 43 with threaded holes 42 for fastening the external threads 41 of the bolt 18. In this case, the bolt 18 and the connector 43 can serve as fixing parts, as long as a through hole (first through hole) 44 and a pin hole 45 are provided in the connector 43.

[0034] Furthermore, in the above embodiments, the bolts 18 installed on the ball joints 16 of each passive link 13, 14, 15 are respectively provided on each passive link 13, 14, 15. However, instead of this, as shown in FIG9, the paired ball joints 16 may also adopt a structure including two ball heads 17 and an integrally formed bolt (fixing part) 46 connecting the two ball heads 17. In this case, the bolt 46 is provided with one or more through holes (first through holes) 47 or threaded holes (first threaded holes, not shown in the figure) and one or more pin holes 48. In this case, the passive link unit including the ball joints 16 can be removed from the drive links 10, 11, 12 and the movable part 3 without disassembling the support link 22.

[0035] Therefore, if the construction involves directly removing the socket 20 from the driven links 13, 14, and 15 along the long axis without rotating it around the long axis of the driven links 13, 14, and 15, then the two ball joints 16 and a single bolt 18 can be exchanged as a unit. Alternatively, the ball joints 16 can be exchanged by exchanging the entire driven link unit. [Simplified Explanation of the Diagram]

[0008] [Fig. 1] shows a front view of a parallel robot according to one embodiment of the present invention. [Fig. 2] shows a front view of a partial cross-section of the passive link, drive link, and movable parts of the parallel robot of Fig. 1. [Fig. 3] shows a longitudinal section of the support link of the parallel robot of Fig. 1. [Fig. 4] shows a front view of a partial cross-section of the ball joint exchange procedure between the passive link and the drive link of Fig. 2. [Fig. 5] shows a front view of a partial cross-section of the state in which the passive link is detached from the drive link during the ball joint exchange operation of Fig. 4. [Fig. 6] shows a front view of a partial cross-section of a first modified example of the parallel robot of Fig. 1. [Fig. 7] shows a front view of a partial cross-section of a second modified example of the parallel robot of Fig. 1. [Fig. 8] shows a front view of a partial cross-section of a third modified example of the parallel robot of Fig. 1. [Fig. 9] shows a front view of a partial cross-section of a fourth modified example of the parallel robot of Fig. 1.

Claims

1. A parallel robot, comprising: Base section; Movable parts are arranged relative to the base portion with a gap between them; The system comprises a plurality of robotic arms that connect the base portion and the movable component in parallel. Each robotic arm includes: a drive link that is driven to rotate by a motor provided on the base portion; two parallel passive links that connect the drive link to the movable component; a ball joint disposed between each passive link and the drive link and between each passive link and the movable component; and a mounting mechanism that detachably mounts each ball joint to the drive link or the movable component. Each ball joint includes: a ball head and a fixing portion integrally formed on the ball head. At least one of the mounting mechanisms between each passive link and the drive link and between each passive link and the movable component of each robotic arm includes: a first threaded hole or a first through hole disposed on the fixing portion. A second through hole or a second threaded hole is provided in the drive link or the movable part; and a screw component is provided, which passes through the first through hole and is fastened to the second threaded hole, or passes through the second through hole and is fastened to the first threaded hole; while maintaining the interval between the two passive links, after releasing the fastening of the screw component, the mounting part provided on the drive link or the movable part side is moved relative to the passive link in the length direction, thereby enabling the ball joint and the passive link to be separated from the drive link or the movable part.

2. The parallel robot as described in claim 1, wherein, The fixing part of the two ball joints is integrally formed, and the two ball joints are disposed at at least one of the passive links and the drive links of each robotic arm and between each passive link and the movable part.

3. The parallel robot as described in claim 1 or 2 further includes a support link spanning between the two passive links of each of the robotic arms and connecting the two passive links; and the support link is mounted to each of the passive links in a manner that allows it to rotate about an axis orthogonal to the major axis of the passive link.

4. The parallel robot as described in claim 3, wherein, The two passive connecting rods, each with a ball joint at both ends, are connected by the support connecting rod to form a unit, which is then detachably installed on the drive connecting rod and the movable part.

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